ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 275 



Microscopical Examination of Blast-furnace Slag.* — H. Passow 

 indicates the great value of microscopical examination of blast-furnace 

 slag for determining its suitability for making Portland cement. Vitreous 

 slag is required for this purpose, and while chemical analysis fails to dis- 

 tinguish between vitreous and non-vitreous slags, microscopical examina- 

 tion of crushed particles gives the required information. 



Ducelliez, F.— Cobalt-silver Alloys. 



Procis-verbaux des stances de la SociMe des Sciences 

 physiques et naturelles de Bordeaux, 1909-10, 



pp. 46-8. 



,, ,, Cobalt-zinc Alloys. Tom. cit., pp. 102-11 (1 fig.). 



Peirce, B.O. — The Resistivity of Hardened Cast-iron as a measure of its Temper 

 and of its Fitness for use in Permanent Magnets. 



Proc. Amer. Acad. Arts and Sciences, xlvi. (1910) 



pp. 185-204 (10 figs.). 



,, ,, The Magnetic Permeabilities at low Excitations of two kinds of 

 very pure soft Iron. Tom. cit., pp. 207-12. 



Vigourocx, E. — Nickel-silver System. 



Proce's-verbaux des stances de la Socicti des Sciences physiques 

 et naturelles de Bordeaux, 1909-10, pp. 44-5. 



Vigouroux, E., & A. Bourbon — Mutual Action of Nickel and Zinc. 



Tom. cit., pp. 95-102 (1 fig.). 



Stahl und Eisen, xxx. (1910) pp. 989-93 (3 figs.). 



